1. Field of the Invention
The present invention relates to a microscope used for observing a sample such as a semiconductor device at a predetermined observation plane and through the sample, and a sample observation method.
2. Related Background Art
In recent years, many of semiconductor devices are being fabricated using face down bonding and flip chip bonding with a device surface (active circuit surface) at the bottom side of a substrate. In inspection of such semiconductor devices, it is sometimes difficult to expose the device surface of the substrate without disassembling a package, depending upon a type of the package and a mounting direction. Even in cases where a device surface of a substrate mounted not using the flip chip mounting can be exposed, but where semiconductor devices are highly integrated or multilayered, it is becoming hard to observe interconnections, devices, etc. in lower layers. Correspondingly, a method proposed is one of observing a semiconductor device through a substrate from the back side opposite the device surface.
The conventional known semiconductor inspection apparatus include an emission microscope (Japanese Patent Application Laid-Open No. H7-190946), an OBIRCH device (Japanese Patent Application Laid-Open No. H6-300824), a time-resolved emission microscope (Japanese Patent Application Laid-Open No. H10-150086), and so on. In observation using such microscopes, since silicon (Si) used as a material of the substrate of the semiconductor device transmits near-infrared light, the observation is carried out using infrared light or the like. In recent years, however, the semiconductor devices as inspected objects are being miniaturized more and more, and it is becoming hard for the conventional inspection apparatus using visible light or infrared light, to analyze the microstructure, because of restrictions from the diffraction limit in the optical system.
For this reason, in a case where the microstructure of a semiconductor device is analyzed to detect an abnormal portion in a circuit pattern such as transistors and interconnections formed in the semiconductor device, an abnormality-existing range is first narrowed down to some extent by an inspection apparatus using visible light or infrared light. Then the narrowed-down range is further observed by a method with an observation apparatus such as an electron microscope with higher resolution to detect an abnormal portion in the semiconductor device.